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1.
The effects of passive immunization with immunoglobulin Y (IgY) on the pathogenesis of Marek's disease (MD) were examined in an experimental line of White Leghorn chickens highly susceptible to MD. Purified IgY with anti-MDV antibody activity, when injected into chicks, delayed the development of MDV viremia and lesions until 9 days postinoculation (PI) with Marek's disease virus (MDV). The blastogenic response of spleen cells to concanavallin-A was depressed at 6 days PI in the birds without passive immunization, whereas it was not totally depressed until 17 days in birds passively immunized with IgY anti-MDV antibody.  相似文献   

2.
Histocompatible B13/B13 white specific-pathogen-free leghorn chickens were used to investigate the effect of coinfection with Cryptosporidium baileyi and the HPRS 16 strain of Marek's disease virus (MDV) in chickens and to assess the pathogenicity of C. baileyi when MDV is given before or after the parasite. Groups of chickens concurrently infected with C. baileyi orally inoculated at day (D)4 and MDV inoculated at hatching (C4M0 group) or at D8 (C4M8 group) were compared with relevant control groups inoculated with only C. baileyi at D4 (C4 group), only MDV at hatching (M0 group) or at D8 (M8 group), and an uninoculated control group (UC group). The chickens were kept in isolator units until the end of the experiment at D62. Our results showed a considerable synergistic effect in concurrently infected chickens and more severe consequences when chickens received MDV before C. baileyi infection. In fact, except for a slight transitory weakness, the chickens in C4 group remained free of overt clinical signs and there was no mortality. However, coinfection with both pathogens induced more lasting or permanent oocyst shedding. Severe clinical cryptosporidiosis with weakness, anorexia, depression, growth retardation, and chronic and severe respiratory disease causing death occurred in all chickens in the C4M0 group between D12 and D43 and in 67% of the chickens in the C4M8 group between D17 and D57. Eighty-two percent and 33%, respectively, died before the development of specific Marek's disease lesions. Mortality rates were 27% and 33% in the M0 and M8 groups, respectively. The presence of MDV enhanced the establishment of more lasting cryptosporidial infection in the respiratory tract, esophagus, crop, proventriculus, and kidneys (only in C4M0 group) as well as in bursa of Fabricius, ceca, and cloaca. Serologic analysis showed that chickens with chronic cryptosporidiosis in the C4M8 group had an increased level of C. baileyi-specific immunoglobulin A. Our results may explain some cases of mortality in chickens naturally infected with MDV and Cryptosporidium.  相似文献   

3.
A Marek's disease (MD) lymphoblastoid cell line, MDCC-MSB1-41C, was highly transplantable and lethal for chickens. Autopsies showed extensive metastasis in various organs. The transplantabilities of the parent cell line, MDCC-MSB1, and another derivative line, MDCC-MSB1-33C, were transient. MD virus (MDV) could be isolated from the kidneys but not from the peripheral blood leukocytes of chickens inoculated with the MSB1-41C cell line. In addition, anti-MDV antibodies were produced both in chickens inoculated with this cell line and in controls raised with inoculated chickens, but several attempts to isolate MDV from this cell line in vitro failed.  相似文献   

4.
Studies were performed to determine if passive immunization with hyperimmune sera generated to specific Newcastle disease virus (NDV) proteins conferred protection against virus challenge. Six groups of 3-wk-old chickens were passively immunized with antiserum against either hemagglutinin-neuraminidase/fusion, (HN/F) protein, nucleoprotein/phosphoprotein (NP/P), Matrix (M) protein, a mixture of all NDV proteins (ALL), intact ultraviolet-inactivated NDV (UVNDV), or negative sera. Blood samples were collected 2 days postimmunization, and the birds were challenged with Texas GB strain of NDV. Antibody titers were detected from those recipient birds that had received the antisera against the HN/F, ALL, or UVNDV by a hemagglutination inhibition test, an enzyme-linked immunosorbent assay (ELISA), and a virus neutralization test. Antibodies were detected only by the ELISA from the birds that had received antisera against NP/P and M protein. Antibody titers in the recipient birds dropped by two dilutions (log2) after 2 days postinjection. Birds passively immunized with antisera against HN/F, ALL, and UVNDV were protected from challenge, whereas chickens passively immunized with antisera against NP/P and M protein and specific-pathogen-free sera developed clinical signs of Newcastle disease. The challenge virus was recovered from the tracheas of all passively immunized groups. The presence of neutralizing antibodies to NDV provided protection from clinical disease but was unable to prevent virus shedding from the trachea.  相似文献   

5.
Immuno- and enzyme-histochemical staining procedures were used to investigate in vivo the interaction of Marek's disease virus (MDV) with splenic non-lymphoid cells. The newly developed monoclonal antibody D-35.1, which recognizes all three MDV serotypes, was used to study the localization of MDV at various times after intramuscular inoculation of 1-day-old chicks with MDV strain K. The D-35.1-positive cells were detected in the bursa of Fabricius, spleen, thymus, proventriculus, and cecal tonsils, and the number of chickens showing the cells increased between days 4 and 10. From day 21, the skin of the chickens contained D-35.1-positive feather follicles. The D-35.1 monoclonal antibody did not stain any cells in peripheral blood, nerves, kidney, and gonads at any time. In addition, D-35.1-positive cells were not detected in lymphoproliferative lesions in visceral organs and peripheral nerves. Double staining procedures on serial sections using monoclonal antibody CVI-ChNL-68.2, specific for splenic ellipsoid-associated reticulum cells, revealed that the majority of D-35.1-positive cells were situated in the peri-capillary sheath of reticulum cells at day 10. The sheath of cells detected by monoclonal antibody CVI-ChNL-68.2 was disrupted, and they were clustered around D-35.1-positive cells. These results support the hypothesis that ellipsoid-associated reticulum cells are involved in the early pathogenesis of Marek's disease.  相似文献   

6.
Recent studies have emphasized the crucial role of gut microbiota in triggering and modulating immune response. We aimed to determine whether the modification of gut microbiota by oral co‐administration of two antibiotics, ampicillin and neomycin, would lead to changes in the antibody response to antigens in chickens. Neonatal chickens were given or not given ampicillin and neomycin (0.25 and 0.5 g/L, respectively) in drinking water. At 2 weeks of age, the chicks were muscularly or orally immunized with antigenic keyhole limpet hemocyanin (KLH), and then serum anti‐KLH antibody levels were examined by ELISA. In orally immunized chicks, oral antibiotics treatment enhanced antibody responses (IgM, IgA, IgY) by 2–3‐fold compared with the antibiotics‐free control, while the antibiotics did not enhance antibody responses in the muscularly immunized chicks. Concomitant with their enhancement of antibody responses, the oral antibiotics also lowered the Lactobacillus species in feces. Low doses of antibiotics (10‐fold and 100‐fold lower than the initial trial), which failed to change the fecal Lactobacillus population, did not modify any antibody responses when chicks were orally immunized with KLH. In conclusion, oral antibiotics treatment enhanced the antibody response to orally exposed antigens in chickens. This enhancement of antibody response was associated with a modification of the fecal Lactobacillus content, suggesting a possible link between gut microbiota and antibody response in chickens.  相似文献   

7.
In chickens experimentally infected with Marek's Disease virus (MDV) an increased amount of immunoglobulin G is produced. Using a technique of quantitative crossed immunoelectrophoresis it has been shown, that 70% of this immunoglobulin G is non-specific. Only 18% could be absorbed with MDV strain CPRL VII-infected chicken kidney cells, and only 5% with MDV-induced lymphoblastoid cells of the MDCC-MSB1 cell line. It is hypothesized that the production the unspecific immunoglobulin G is caused by a polyclonal stimulation of B-cells.  相似文献   

8.
Antibody directed against Marek's disease-associated tumor surface antigen (MATSA) was eluted from tumor cells of lymphomas and peripheral blood lymphocytes that were isolated from Marek's disease virus-infected chickens. Feather follicular Marek's disease virus (MDV) antigen could not be demonstrated with this antibody by indirect immunofluorescent (IF) staining. Monoclonal antibody directed against MATSA could completely block the activity of eluted antibody and vice versa. By indirect IF staining using eluted antibody and fluorescein isothiocyanate (FITC) labelled antichicken globulin conjugate. MATSA-bearing cells were detected in MDV infected and herpes virus of turkey (HVT) vaccinated birds. Blocking of immunoglobulin molecules present on B-cells by anti-chicken globulin is critical in this test.  相似文献   

9.
The H5 gene of avian influenza virus (AIV) strain A/chicken/Malaysia/5744/2004(H5N1) was cloned into pcDNA3.1 vector, and Esat-6 gene of Mycobacterium tuberculosis was fused into downstream of the H5 gene as a genetic adjuvant for DNA vaccine candidates. The antibody level against AIV was measured using enzyme-linked immunosorbent assay (ELISA) and haemagglutination inhibition (HI) test. Sera obtained from specific-pathogen-free chickens immunized with pcDNA3.1/H5 and pcDNA3.1/H5/Esat-6 demonstrated antibody responses as early as 2 weeks after the first immunization. Furthermore, the overall HI antibody titer in chickens immunized with pcDNA3.1/H5/Esat-6 was higher compared to the chickens immunized with pcDNA3.1/H5 (p < 0.05). The results suggested that Esat-6 gene of M. tuberculosis is a potential genetic adjuvant for the development of effective H5 DNA vaccine in chickens.  相似文献   

10.
Bursa- and thymus-dependent functions were examined in Marek's disease (MD)-susceptible normal chickens and in chickens treated with 5 and 16 mg of cyclophosphamide (CY) at the time of hatching. Chickens not exposed to Marek's disease virus (MDV) and treated with CY temporarily lost mitogenic response to concanavalin A but regained full response after 5 weeks. Bursa-dependent functions, such as presence of germinal centers in spleen and cecal tonsils, morphologic features of bursa, and sheep red blood cell antibody response were completely lost in chickens treated with 16 mg of CY and only partly retained in chickens treated with 5 mg of CY. In chickens exposed to MDV, the degree of thymus-dependent spleen cell mitogenic response was directly related to frequency and severity of MD. Chickens treated with 16 mg of CY had a mild mitogenic depression and low frequency and severity of MD lesions, whereas those treated with 5 mg of CY and those not treated had marked mitogenic depression and high frequency and severity of MD. Suppressions of bursa- and thymus-dependent functions by MDV alone were also evident when comparing MDV-exposed and nonexposed chickens. The results also indicate that presence of small, residual amounts of humoral factor(s) may enhance MDV oncogenesis.  相似文献   

11.
The effect of infection by various strains of Marek's disease virus (MDV) on the immune function of 3-week-old chickens was examined. MDV strains of low (CU-2, RB-7) and high (RB-3, MD-5, and MD-11) pathogenicity were compared with prototype JM-10 strain of moderate pathogenicity. Mortality, whole body weight, relative weights of lymphoid organs, histopathology, humoral antibody responses to thymus-dependent and -independent antigens, and in vitro lymphocyte responses to mitogen stimulation were investigated at 1, 2, and 3 weeks postinfection. MDV strains of high pathogenicity significantly depressed responses at 3 weeks postinfection, seeming to indicate the ability of these viruses to induce severe immunodepression. However, the fact that the moderately pathogenic and even some of the low-pathogenicity strains induced immunodepression suggests that other viral mechanisms are also important in its determination.  相似文献   

12.
Both Marek's disease virus (MDV) and chicken infectious anemia virus (CIAV) infections are prevalent in chickens throughout the world. In the past decade, MDV strains with increased virulence (very virulent plus MDV pathotype [vv+MDV]) have been isolated. The purpose of this experiment was to determine the effects of coinfection of chickens with CIAV and a vv+MDV isolate. Specific-pathogen-free chickens were inoculated at 1 day posthatch with RB1B (very virulent MDV pathotype [vvMDV]) only, 584A (vv+MDV) only, CIAV only, RB1B + CIAV, 584A + CIAV, or nothing. Samples of spleen, thymus, and bursa of Fabricius were collected at 4, 7, 10, and 13 days postinoculation (DPI). Thymic and bursal atrophy at 13 DPI and final mortality at 30 DPI were significantly greater in chickens inoculated with 584A with or without added CIAV, or with RB1B plus CIAV, compared with birds inoculated with RB1B alone. Both amounts of virus reisolated and levels of virus detected by quantitative-competitive polymerase chain reaction were greater at 4 DPI in 584A inoculates compared with RB1B inoculates. To monitor the early cytolytic infection, northern analysis was done with a probe for the MDV immediate early gene ICP4 (infected cell protein 4). In the absence of CIAV, ICP4 expression was more apparent in chickens inoculated with 584A than in those inoculated with RB1B. CIAV coinfection increased ICP4 expression in the spleens of chickens infected with RB1B. These results indicated that inoculation of chickens with the 584A isolate caused a more robust early cytolytic infection compared with inoculation with RB1B alone and support the classification of 584A as a vv+MDV strain. Coinfection with CIAV exacerbated vvMDV strain RB1B infection. The extent of this exacerbation was less evident when birds were coinfected with 584A and CIAV.  相似文献   

13.
We recently reported a comparison of glycoprotein-encoding genes of different Marek's disease virus pathotypes (MDVs). One mutation found predominantly in very virulent (vv)+MDVs was a 12-bp (four-amino acid) deletion in the glycoprotein L (gL)-encoding gene in four of 23 MDV strains examined (three were vv+MDVs and one was a vvMDV). This mutation was noted in the gL of the TK (615K) strain, but not in the RL (615J) strain of MDV. These strains have identical mutations in the meq gene characteristic of vv+MDVs but can be distinguished by the mutation in the gL-encoding gene. The TK strain was originally isolated from vaccinated chickens and appeared to confer or enhance horizontal transmission of the vaccine virus, herpesvirus of turkeys (HVT). Because the molecular basis for increased virulence of MDV field strains is unknown, we hypothesized that one mechanism might be by coreplication of MDV-1 strains with HVT and that it could be mediated by the mutation of gL, an essential component of the glycoprotein H/L complex. In this study, we compared the pathogenicity of TK (615K) and RL (615J) strains of MDV in the presence and absence of simultaneous HVT coinfection. MDV infections were monitored at the levels of viremia (for both MDV-1 and HVT), clinical signs of MD, tumor incidence, and mortality in 1) inoculated chickens, 2) chickens exposed at 1 day of age, 3) chickens exposed at 2 wk of age, and 4) chickens exposed to both TK/HVT- and RL/HVT-infected chickens at 6 wk of age. We found high incidences of clinical MD signs in all inoculated treatment groups and all chickens exposed to TK and RL viruses, regardless of the presence of HVT. The median time to death of chickens exposed to TK1HVT-infected chickens, however, was lower than the other treatment groups for contact-exposed chickens. Although this difference was not considered to be statistically significant to a rigorously interpreted degree because of the removal of chickens for sampling from the test groups, these data suggest that replication of the TK strain and HVT, when coadministered, might incrementally affect the virulence of MDV-1 strains. The strict correlation of this enhancement of virulence with the mutation in gL, however, requires additional experiments with genetically identical MDV background strains.  相似文献   

14.
In the genome of strains of very virulent Marek's disease virus serotype 1(vvMDV1), such as Md5 and RB1B, the meq open reading frame (ORF) encoding a 339-amino-acid bZIP protein, is present, while a slightly longer meq ORF, termed as L-meq, in which a 180-bp sequence is inserted into the meq ORF is found in other strains of MDV1, such as CV1988/R6 and attenuated JM. When chickens were infected with vvMDV1 strains and the meq gene was amplified by nested polymerase chain reaction (PCR), the meq gene was detected throughout the experimental period for 7 weeks post inoculation (pi). However, the L-meq gene was also detected at 3 to 5 weeks and 3 to 4 weeks pi. in Md5-infected and RB1B-infected chickens, respectively. In the case of chickens infected with an attenuated MDV1, the JM strain, the L-meq gene was detected at 2 to 7 weeks pi., and the meq gene was also detected at 2 to 6 weeks pi. Both L-meq and meq genes were detected in chickens infected with an attenuated nononcogenic vaccine strain of MDV1 (CVI988/R6), throughout the experimental period. Though quantitative PCR was not performed, a larger amount of the PCR products corresponding to the L-meq than the meq gene was amplified from chickens infected with JM or CVI988/R6. These results suggest that a dynamic population shift between the MDV subpopulations displaying meq and L-meq genes occurs in chickens during the course of MDV infection. Since the MDV subpopulation that displays the L-meq gene only displays it during the latent phase, the L-meq and its gene product, if any, might contribute to the maintenance of the MDV latency.  相似文献   

15.
Two experiments were used to examine the potential role of IFN-gamma in chickens infected with reticuloendotheliosis virus (REV) and Marek's disease virus (MDV). First, chickens were infected with REV and/or MDV at 5 days of age and examined from 3 to 50 days post-infection (dpi). In REV+MDV co-infection chickens, IFN-gamma ELISA demonstrated a 3-fold increase at 7 dpi compared to the controls, while REV alone caused a 5-fold increase, the IFN-gamma levels peaked, and then gradually decreased. IFN-gamma levels significantly decreased in MDV infection at 3 dpi and 15 dpi. Second, experiments were designed to determine the effects of different viruses and ConA on IFN-gamma production. For REV- or MDV-infected chickens, the IFN-gamma levels decreased slightly after adding ConA. This is the first report of IFN-gamma production in SPF chickens infected with REV and MDV measured by directly quantitative method.  相似文献   

16.
Zhang Y  Sharma JM 《Avian diseases》2001,45(3):639-645
CVI988, a serotype 1 Marek's disease virus (MDV), was used as an in ovo vaccine in specific-pathogen-free chickens to determine if this virus induces early posthatch protection against Marek's disease as has been shown previously for turkey herpesvirus. MDV CVI988 was injected at embryonation day (ED) 17 (group 1) or at hatch (group 2). A third group (group 3) was left unvaccinated. At 1, 2, 3, 4, 5, and 7 days of age, chickens from each group were sampled and examined as follows: a) single-cell suspensions of spleen were inoculated onto chicken embryo fibroblast monolayers to isolate the virus; b) sections of bursal tissues were stained by indirect immunofluorescence assays with anti-pp38 monoclonal antibody to identify viral antigen expression; and c) chickens were exposed intra-abdominally to MDV RB1B, a virulent serotype 1 MDV. Results revealed that in chickens given MDV CVI988 at ED 17, virus and virus-encoded protein were not detected until chickens were 3 and 2 days old after hatching, respectively. Results also indicated that during the first 4 days after hatch, the chickens given MDV CVI988 at ED 17 were better protected against virulent MDV than those given MDV CVI988 at hatch (P < or = 0.001). These results suggested that MDV CVI988 proteins were adequately expressed in the embryo to initiate prehatch immunologic response. Additional efforts with more sensitive techniques than used in this study are needed to identify the nature of viral expression in embryos.  相似文献   

17.
IgY is a chicken egg yolk antibody which has been used for treatment and prophylaxis of gastrointestinal infections. Our aim was to verify if IgY obtained from chickens immunized with EPEC O111, STEC O111 and STEC O157 is able to show in vitro reactivity and biological activity towards the three bacteria. IgY was obtained from eggs laid before and after immunization with each bacterium. The preparations of IgY anti-EPEC O111 and anti-STEC O111 shared high reactivity detected by ELISA and growth inhibition ability towards both bacteria EPEC O111 and STEC O111. Nevertheless, the preparation of IgY anti-STEC O157 showed high reactivity and growth inhibitory effect only towards the homologous strain. Our results showing in vitro biological activity of IgY reinforce its use as an alternative for the treatment or prophylaxis of E. coli infections and encourage the development of in vivo studies for a possible future human therapeutic use.  相似文献   

18.
For the easy survey of Marek's disease virus (MDV), feather tip-derived DNA from MDV-infected chickens can be used because feather tips are easy to collect and feather follicle epithelium is known to be the only site of productive replication of cell-free MDV. To develop a diagnostic method to differentiate highly virulent strains of MDV from the attenuated MDV vaccine strain, CVI988, which is widely used, nested polymerase chain reaction (PCR) was performed to detect a segment of the meq gene in feather tip samples of chickens experimentally infected with MDV. In chickens infected with Md5, a strain of oncogenic MDV, the meq gene was consistently detected, whereas the L-meq gene, in which a 180-base pair (180-bp) sequence is inserted into the meq gene, was detected in CVI988-infected chickens. Moreover, the meq gene was mainly detected even in chickens co-infected with both Md5 and CVI988. These results suggest that this method is appropriate for the surveillance of the highly virulent MDV infection in the field.  相似文献   

19.
淋巴细胞凋亡抑制与鸡马立克氏病的发生   总被引：3，自引：1，他引：2  
本研究证明，外源性糖皮质激素（ＧＣ）可以诱导正常鸡和马立克氏病毒（ＭＤＶ）疫苗免疫鸡淋巴细胞ＤＮＡ出现１８０～９００ｂｐ的阶梯状小分子断片，即诱导淋巴细胞凋亡过程启动。尤其是疫苗免疫鸡淋巴细胞对体内生理浓度ＧＣ就有相当高的致ＤＮＡ阶梯状小分子断裂的敏感性。而这种诱导反应可以被ＲＵ４８６阻断，人工感染ＭＤＶ鸡同样有抑制该反应的作用，这暗示ＭＤＶ引起无免疫活性淋巴细胞在鸡体内堆集直到形成肿瘤，可能与ＭＤＶ抑制淋巴细胞凋亡，使自体生理性清除非功能性淋巴细胞的机制受阻有关。本研究还以ＲＵ４８６阻断鸡淋巴细胞糖皮质激素受体（ＧＲ）。结果使鸡对ＭＤＶ敏感性提高，ＭＤ病变形成提前。  相似文献   

20.
Dilution of Marek's disease (MD) vaccines is a common practice in the field to reduce the cost associated with vaccination. In this study we have evaluated the effect of diluting MD vaccines on the protection against MD, vaccine and challenge MD virus (MDV) kinetics, and body weight when challenged with strains Md5 (very virulent MDV) and 648A (very virulent plus MDV) by contact at day of age. The following four vaccination protocols were evaluated in meat-type chickens: turkey herpesvirus (HVT) at manufacturer-recommended full dose; HVT diluted 1:10; HVT + SB-1 at the manufacturer-recommended full dose; and HVT + SB-1 diluted 1:10 for HVT and 1:5 for SB-1. Vaccine was administered at hatch subcutaneously. One-day-old chickens were placed in floor pens and housed together with ten 15-day-old chickens that had been previously inoculated with 500 PFU of either Md5 or 648A MDV strains. Chickens were individually identified with wing bands, and for each chicken samples of feather pulp and blood were collected at 1, 3, and 8 wk posthatch. Body weights were recorded at 8 wk for every chicken. Viral DNA load of wild-type MDV, SB-1, and HVT were evaluated by real time-PCR. Our results showed that dilution of MD vaccines can lead to reduced MD protection, reduced relative body weights, reduced vaccine DNA during the first 3 wk, and increased MDV DNA load. The detrimental effect of vaccine dilution was more evident in females than in males and was more evident when the challenge virus was 648A. However, lower relative body weights and higher MDV DNA load could be detected in chickens challenged with strain Md5, even in the absence of obvious differences in protection.  相似文献   

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